1. Field of the Invention
The present invention relates to tractor trailer rigs and more particularly to an improved locking apparatus that locks the rear doors of such a trailer using a pair of spaced apart structural blocks that receive a hollow spanning member or bar transversely positioned to span between the blocks. One of the blocks has a vertical channel that receives a locking member that attaches to the spanning member during use and that can be keyed or provided with a tumbler.
2. General Background of the Invention
Most large trailer configurations such as the tractor trailer rig (commonly referred to by the nickname "eighteen wheeler") have a pair of pivotally mounted rear doors that can be opened to completely expose the cargo area. One of the problems facing the cross country trucking industry is the theft of tractor trailer rigs that are stored temporarily and disconnected from the truck or tractor portion. These trailers can be stolen using an additional truck or tractor trailer occupied by the thief. If the thief obtains access to the bill of lading, forced entry to the trailer can result in loss of all or part of the cargo even if the trailer is not stolen. Thus, pilfering from an unintended trailer can be a problem, as when one is in "piggyback" transit by rail or when it is in a yard unattended by a tractor operator without an attached tractor.
One of the problems that faces the operator of truck lines or an individual truck owner is that of the bill of lading that is often fastened or taped to the rig of the truck in plain view. If the thief is able to review the bill of lading, the thief knows the value, or at least the approximate value, of the contents.
There have been many locking systems for truck doors that have been patented. An example of such a patent is the Silverman U.S. Pat. No. 3,601,453 entitled "Safety Lock for Trailer Doors". The '453 patent discloses a locking apparatus for a trailer door wherein a power lock for the door is mounted in a position inaccessible from the outside of the trailer and for its operation, requires power such as air pressure or 12 volt electricity, which is available from a tractor, to unlock it.
The Panici U.S. Pat. No. 3,813,119 discloses a protection system for box car doors. In the '119 patent, a latch system includes a pneumatic cylinder with suitable linkage and two metal arms with hooks formed at end. When air pressure is applied to the cylinder, hooks unlatch. As air pressure is released, spring returns cylinder piston to its original position, thereby latching the doors closed.
An anti-theft door locking apparatus is the subject of U.S. Pat. No. 3,843,174. The apparatus is for use with semitrailers, delivery vans, railway cars, and similar freight storage and transport vehicles to prevent pilferage from the freight compartments thereof. The apparatus includes a reciprocal locking pin selectively movable between an active position in cooperative engagement with the access door of a freight compartment to constrain the door in the closed position thereof and an inactive position releasing such door for movement. The locking pin is controlled by plunger means movable between operative and inoperative positions respectively corresponding to the active and inactive positions of the locking pin and connected therewith so as to control the position thereof. The plunger means are biased toward the operative position thereof by spring structure which therefore tends to maintain the locking pin in its active position, and selectively operative energizing means which may be mechanical in nature or pneumatic, depending upon the embodiment of the invention, are effective to displace the plunger means against the biasing force of such spring and thereby displace the locking pin into its inactive position. Special equipment such as a source of compressed air provided by the tractor of a tractor-semi-trailer rig or a forklift truck capable of providing a pulling force of substantial magnitude is required to supply the energizing means required to displace the locking pin into its inactive position. However, such special equipment is generally available to authorized personnel but not to those who might pilfer freight. The apparatus also includes operation-inhibiting means in the form of an abutment component or a detent and recess arrangement to hold the locking pin in its inactive position once it has been appropriately displaced thereinto so as to prevent inadvertent or unauthorized return movement of the locking pin into the active position thereof.
In the Morvai U.S. Pat. No. 4,023,388, there is provided a lock cover device particularly intended for use with so-called mortise locks. The device is fabricated of resilient polymeric material which may be readily mounted over the mortise lock, normally without the requirement for completely removing the lock from its mounted position and is characterized by the incorporation of a movable shutter member selectively shiftable between a stable sealing position and a stable keyway exposing position, the assembly including resilient cam and follower means for selectively biasing the shutter to one or the other of said stable positions, the shutter being preferably unstable at any intermediate position.
In the Dohanyos U.S. Pat. No. 4,157,653, there is provided a shielded lock assembly incorporating a body surrounding a deadbolt subassembly. The body renders more difficult access to the deadbolt subassembly in order to reduce the incidence of theft involving the prying, cutting, or other destruction of the deadbolt subassembly. In one embodiment of the invention, the deadbolt subassembly is received within a retaining cage which is itself received within the body. Aperture means are provided in the body and the retaining cage which are adapted to receive at least one locking bracket or staple in locking alignment with the deadbolt.
A trailer door lock system is disclosed in U.S. Pat. No. 4,627,248 issued to David Haworth. The Haworth patent discloses a lock device for a hinged cargo door of a truck trailer that has a housing with a vertically extended groove in one side wall for receiving the rotatable cargo door lock bar. A transversely extended lock pin in the housing is transversely movable through an opening in the same side wall for insertion into a registered hole in the cargo door lock bar in the locked position thereof. Transverse movement of the lock pin is controlled by a simple lock mechanism including a key operated lock shaft having a rocker arm rotatable therewith and having a free end connected to the lock pin for transverse movement of the lock pin in response to rotation of the lock shaft.
A secured locking device is the subject of U.S. Pat. No. 5,062,669 issued to McManigal et al. The '669 patent discloses a lock mechanism for safely locking doors, such as trailer-tractor vehicle doors and for controllably releasing same including a reciprocal or rotatable locking member such as a sliding bolt movable up through the floor of a trailer to a first locking position wherein a door is positively locked and a release position wherein the vehicle door is released with the locking member housed in a tamper-proof box with a pivotal panel that is held shut by a latch released by a latch operator means which is activated by an air drive that can be primarily operated only when connected to the air pressure system of a vehicle.
U.S. Pat. No. 5,685,578 issued to Schneider discloses a door locking mechanism for use with a door having a door latch assembly and a stationary catch including a locking rod movable between a locking position and a release position. In its locking position, the locking rod extends into aligned passages formed in a latch member and a stationary catch member of a door latch assembly, which are engaged with each other in a latched position to maintain the door in a closed position. This prevents disengagement of the latch member from the catch member, to prevent opening of the door. In its release position, the locking rod is withdrawn from at least the latch member passage, to enable the latch member to be disengaged from the catch member and to allow opening of the door. The locking rod is interconnected with a piston disposed within a cylinder. A spring urges the piston toward a position placing the locking rod in its locking position. Fluid pressure is selectively provided to the side of the piston opposite the spring, for selectively overcoming the biasing force of the spring and to move the piston to a position placing the locking rod in its release position. The locking mechanism can be advantageously used with a trailer having a pneumatic system, such that supply of pressurized air in the trailer's pneumatic system is communicated to the piston to place the locking rod in its release position whenever a source of air pressure exceeding a predetermined threshold is connected to the trailer's pneumatic system.
These prior art locking arrangements are complicated and do not provide a universal lock arrangement that can be used with virtually every type of pivoting rear door arrangement for a large cargo-type trailer.